Exchange surfaces Flashcards
Explain how smoking causes a smokers cough and how the cough itself can lead to further problems in the lungs over a long period of time (7).
- causes tar
- smoking destroys ciliated epithelium
- cigarette smoke stimulates goblet cells to reduce more mucus
- mucus in airways build up
- the cough is an attempt to increase airflow by removing mucus
- frequent coughing
- damages airways/alveoli
bronchi/bronchioles thicken so flow of air is restricted - damage to alveoli causes reduced surface area for gas exchange.
Explain how refreshing the air in the air sacs helps to maintain a steep diffusion gradient
increases, partial pressure / concentration, of oxygen
(in the air sac) ;
so concentration of oxygen (in the air sac) is higher than
that in the blood ;
decreases, partial pressure / concentration, of
carbon dioxide (in air sac) ;
so concentration of CO2 (in the air sac) is lower than
that in the blood
Describe how you would use a spirometer trace to measure the rate of oxygen uptake (3)
- measure vol of oxygen used
- find difference in height from one peak to another
- measure the time taken to use this O2
- divide volume by time taken
suggest how histamine stimulates smooth muscle contraction (histamine is a cell signalling molecule) (2)
1 (histamine), binds / attaches, to, receptor
/ glycoprotein ;
idea of :
2 in / on, plasma / cell surface, membrane
(of muscle cell) ;
3 complementary (shape) ;
4 triggers response / causes effect, inside
cells ;
what are alternative methods insects use to increase gas exchange?
- Mechanical ventilation – muscular movements of thorax and abdomen, changing pressure in tracheae and tracheoles.
- Collapsible enlarged tracheae/air sacs –
Act as large reservoirs of air, increase volumes of gas exchanged (tracheae made of chitin which is strong but still flexible!)
state the reasons why tracheal fluid slows down diffusion, but moisture increases.
- moist walls facilitate diffusion because gases diffuse more easily across a cell membrane when dissolved in liquid
- volume of tracheal fluid slows down the diffusion process because gas diffusion through liquid is slower than than ai
describe the process of inhalation and exhalation in insects
- inhalation= air moves into the trachea through spiracles- oxygen travels down a concentration gradient towards cells
- exhalation= co2 moves down its own conc. gradient from cells out the spiracles.
what is the role of sphincters in insects?
open and close the spiracles like guard cells in plants to avoid water loss
does the trachea in insects allow gas exchange?
no, the complete rings of chitin are impermeable to gases
describe data from a spirometer
- tidal volume= volume of air that moves in and out of your lungs with each resting breath
- vital capacity= volume of air that can be exhaled when the deepest intake of breathe is followed by the strongest possible exhalation
- total lung capacity= sum of vital capacity + residual volume
- expiratory reserve volume= extra amount of o2 you can force out over normal tidal volume
- residual volume= volume of o2 left in your lungs when you have exhaled as hard as possible (not all o2 can leave lungs, or it would collapse)
- inspiratory reserve volume= maximum volume of air you can breathe in above normal inhalation
describe the tracheal system in insects.
- rigid exoskeleton with a waxy coating impermeable to gases (spiracles are the opening in the exoskeleton of an insect)
- trachea (kept open by complete spirals of chitin) are tubes within the insects respiratory system which lead to narrower tubes called tracheoles.
- end of tracheoles is filled with tracheal fluid: gases can dissolve in this fluid before diffusing to the cells for gas exchange.
- the more tracheoles, the higher the SA
describe the ventilation mechanism in insects
- active insects need a rapid supply of oxygen, this can be achieved by: contracting and relaxing the muscles of the thorax and abdomen. this alters the volume, and therefore pressure inside the trachea draws air in and out.
- during flight the tracheal fluid is drawn into the respiring muscle, this removes fluid from the tracheoles and reduced the diffusion distance between the air and muscle cells, speeding up diffusion.
Describe the gills of fish
- Oxygen dissolves less readily in water
Structure of fish gills in bony fish: - Series of gills on each side of the head
- Each gill arch is attached to two stacks of laments
- On the surface of each filament,there are rows of lamellae
- The lamellae surface consists of a single layer of flattened cells that cover a vast network of
capillaries
Mechanism: - The capillary system within the lamellae ensures that the blood flow is in the opposite direction to
the flow of water - it is a counter-current system - This system ensures the concentration gradient is maintained along the whole
length of the capillary - The water with the lowest oxygen concentration is found adjacent to the most deoxygenated
blood
describe the ventilation mechanism in fish
- The ventilation mechanism in fish constantly pushes water over the surface of the gills and ensures they
are constantly supplied with oxygen (maintaining the concentration gradient) - When the fish open their mouth they lower buccal cavity. This causes the volume inside
the buccal cavity to increase, and pressure to decrease
The pressure is higher outside the mouth of the fish and so water flows into the buccal cavity
The buccal cavity then closes, as its mouth closes, increasing the pressure within the
buccal cavity, decreasing the volume
As water enters pressure begins to build up in the gill cavity and causes the operculum (a flap of tissue
covering the gills)to be forced open and water to exit the fish
